Hi,
i've spent some time on the Microsoft Xbox Live Vision cam (it's pretty
cheap, USB 2.0, nearly uvc 1.0 compliant, has a pretty good image
quality, manual focus, allegedly a 1280x960 sensor (i haven't checked,
it might just upscale, but i don't think so), and supports MJPG and YUYV).
Out of the box, the cam didn't work with linux-uvc - the cam crashed
after the initial SET_CUR on the VideoStreaming ctrl, and didn't
responded to any USB control packets anymore (not even a simple,
non-video related GET_DESCRIPTOR etc.).
I've compared what the UVC driver did (not much, as the cam crashed
really early) with what the Xbox 360 did (using a USB sniffer), and
found out the following two things:
a.) you need to SET_INTERFACE before doing any SET_CUR, or the cam will
crash. (I don't know the USB specs good enough, but I think the cam is
correct here - the cam offers multiple interfaces, because it supports
some "Authentication Mechanism", so you need to select the video part
first. Of course the cam should not crash, rather STALL or whatever.)
b.) The cam requires about ~3sec time after the initial SET_INTERFACE.
I've added the two hacks (not meant for inclusion, just to describe the
problem):
Index: uvc_driver.c
===================================================================
--- uvc_driver.c (revision 125)
+++ uvc_driver.c (working copy)
@@ -1530,6 +1530,8 @@
dev->intf = usb_get_intf(intf);
dev->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;
dev->quirks = id->driver_info;
+
+ usb_set_interface(udev, 1, 0);
/* Parse the Video Class control descriptor */
if (uvc_parse_control(dev) < 0) {
Index: uvcvideo.h
===================================================================
--- uvcvideo.h (revision 125)
+++ uvcvideo.h (working copy)
@@ -241,8 +241,8 @@
/* Maximum number of video buffers. */
#define UVC_MAX_VIDEO_BUFFERS 32
-#define UVC_CTRL_CONTROL_TIMEOUT 300
-#define UVC_CTRL_STREAMING_TIMEOUT 1000
+#define UVC_CTRL_CONTROL_TIMEOUT 5000
+#define UVC_CTRL_STREAMING_TIMEOUT 5000
/* Devices quirks */
#define UVC_QUIRK_STATUS_INTERVAL 0x00000001
With those two changes, the cam works really nice with luvcview.
uvccapture made some trouble, but that might be caused by something else.
Maybe someone a little more intimate could see if this can be added in a
nice way. But I think increasing the timeouts shouldn't hurt (you could
still add a dummy GET_CUR after the set_interface with an increased
timeout, if you don't want to change the timeout globally), and i
believe the set_interface should be done in any way.
regards,
Felix
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